[ExI] Evolved Complexity (was: Re: extropy-chat Digest, Vol 199, Issue 105)
ben at zaiboc.net
Thu Apr 30 07:27:12 UTC 2020
On 30/04/2020 06:04, Rafal wrote:
> On Wed, Apr 22, 2020 at 2:31 PM Re Rose via extropy-chat
> <extropy-chat at lists.extropy.org
> <mailto:extropy-chat at lists.extropy.org>> wrote:
> Ben - Great question! People have attempted to answer this over
> decades and along the way discovered transposons and "jumping
> genes". For the details you could look up the work of prof Barbara
> McClintock, also profs Andrew Pohorille (of NASA Ames) and Stuart
> Basic idea is that sub-systems of highly complex, hierarchical
> systems can split off and transfer from one system to another.
> Viruses are usually considered non living because they are
> obligate parasites and co-opt other organisims' metabolisms to
> So they did not evolve to be a simpler system. They evolved from
> complex systems as a sub-system, not as separate self-sufficient
> organisms. They are not even metabolically complete - ie, they
> can't live on their own, or replicate on their own, and instead
> depend utterly on hosts.
> ### Dunno. There are multiple cases of animals and plants undergoing
> dramatic simplification of their function during both phylogeny and
> ontogeny. There are parasites that started out with having a nervous
> system and then devolved to just chunks of flesh. There are sessile
> marine animals that start out as free-swimming, active larvae and then
> radically simplify their body, while usually increasing in size.
> Animals that lose senses after moving to caves.
> There is no general tendency for any given species to become more
> complex. Depending on the situation, a species can evolve for more
> complexity or devolve - and the actual course of evolution depends on
> the availability of ecological niches adjacent to the niche currently
> occupied by that species. For many species, the mutational catastrophe
> imposes hard limits on available configuration space - they can't just
> build more complexity because the speed of information loss due to
> random mutations exceeds their ability to accumulate new and useful
> (i.e. fitness-enhancing) information.
> On the other hand, the ecosystem as a whole tends to become more
> complex - the existence of one level of complexity (i.e. improved
> intracellular signaling, improved DNA repair, targeted DNA mutation)
> opens the space to explore next levels of development (respectively
> for the above examples, multicellularity, long chromosomes, adaptive
> immune systems), and with enough species available these new levels
> are explored, eventually opening even more opportunities for building
> complexity. Some species evolve, some devolve but the whole ecosystem
> (ecosphere) gets bigger and more complicated, at least until the next
> asteroid strike.
The virus example may be arguable, they are rather bizarre things after
all, but as Rafal points out, there are plenty of examples of
metabolically complete organisms evolving less complexity.
But ecosystems, or at least the ecosphere as a whole, tending toward
more complexity is an interesting idea. If true (which it seems, at
first glance, to be), then evolution /does/ produce more complexity.
That's something I've never considered before, and I'm wondering what
the implications of it might be.
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